Concentration of vitamin e



reams May 1950 GQNCENTBATION 0F VITAMIN E Arthur mnmomuomas. 1., and nuts mum, New; York), N. Y... assignors to The Chemical Foundation, Incorporated. a corporation of Delaware, as trustee No Drawing. Application March 18, 1948, Serial No. 479,868

r Claims. (cum-a1) 0.31% and 0.38% and in soybean oil is betweenabout 0.12% and 0.21% while the content 01' cottonseed and corn oil is of the order of .ll%.

' The desirability of securing higher concentration of these products for use as antioxidants and vitamin E has been recognized and it has been proposed to eflect such concentration by distilling over a tocopherol-containing fraction at a temperature of the order of 145 C. in a cyclic molecular still. By such a method distillates containing of the order of from 14% to 18% of tocopherols may be obtained. Such a distillation however is far from quantative; for example, in the molecular distillation of soybean oil from about to about 50% of the original tocopherols remain in the undistilled residue.

It has now been found that such a concentration may be efi'ected in a simple manner utilizing a continuous low temperature extraction method.

' The improved method is based upon the discovery oi the efllcacy of liquefied normally gaseous hydrocarbons as a solvent i'ractionating agent for the tocopherols as against the associated triglycerides of the oil.

The rationale and mechanism of the process can readily be appreciated from a consideration of the effect of heat on a liquefied hydrocarbonvegetable oil system. It soybean oil is added to liquid propane at room temperature a completely homogeneous solution is formed. It the ratio of solvent-to oil is '7 to 1 then upon heating the solution under pressure to a temperature of about 64 0. two distinct liquid phases are formed. It the ratio of liquid propane to oil is about to 1 two liquid phases will be formed at a slightly higher temperature. It is found that the upper liquid phase will consist primarily of liquid propane plus antioxidants and dissolved oil while the lower liquid phase consists of the remainder of the oil and antioxidants in addition to some dissolved propane. Upon separation of the two phases and removal of the propane by distilla- 2 v tion, it is round that antioxidants oi the tocopherol type are concentrated in the oil traction obtained from the upper or propane phase. With such a simple stage or batch treatment it is found that the enrichment factor is about 2, i. e., the upper phase or fraction contains twice the concentration of tocopherols as that of the original oil.

In the preferred mode oi operation the source material is continuously extracted with the liqueiled solvent in a continuous countercurrent extraction system. It is found that such a method insures an economic extraction and concentration of the desired valuable constituents.

In a typical operation the extraction system is operated utilizing a ratio oi 15 volumes of propane, or equivalent solvent to one of the oil treated. The tocopherol-containing oil may be red continuously to a continuous extraction tower near the upper section and approximately onethird oi the distance from the top, the propane may be fed continuously to the lower section of the tower at a point approximately one-fifth of the distance from the bottom. The upper tocopherol enriched fraction or phase is continuoushr withdrawn from the top oi the tower-and the lower phase is withdrawn from the base of the tower. In such a continuous operation a temperature gradient is maintained in the tower to facilitate the extraction. Prelerably the top of the tower should be maintained at a temperature of about 94 C. and the bottom of the tower at about 70 C. The propane may be recovered from each phase by distillation and may be recycled in the system.

It will be appreciated that the improved meth od presents an eminently simple and effective method of concentrating the desired constituents from a source material in which they occur in very low concentrations. It is particularly to be observed that as compared to earlier methods the improved process ellects the concentration without exposing any of the constituents of the oil to elevated temperatures. This is particularly important in circumstances like the present where the valuable end products are thermolabile.

The concentrates produced by the described method display vitamin E activity and may be employed for this purpose.- These concentrates similarly act as antioxidants for vitamin A and may be utilized for this function with vitamin A concentrates as well as an addition agent to fats to inhibit rancidity.

We claim: 1

l. Amethod of producing tocopherol-contain- 1 ingconcentrate which vegetable 011 containing tocopherols with liquecomprises, contacting a comprises, continuously chargin the oil to the,

upper portion of a pressure extraction zone, continuously charging a liquefied normally gaseous paraillnic hydrocarbon to the lower portion of such zone, adjusting the rate of flow of the oil and solvent such that an oil to solvent ratio of approximately 1 to 15 by volume is maintained in the zone; maintaining a temperature of the order of about 70 C. at the bottom and a temperature of about 94 C. at the top of the zone; continuously withdrawing a fraction from the top of the zone and a fraction from the base of the zone, separating the hydrocarbon from the withdrawn upper fraction to recover an oil fraction enriched in tocopherols.

3. The process of treating tocopherol-containing vegetable i'atty oil to obtain an oil fraction enriched in tocopherols which comprises, contacting the tocopherol-containing oil in a continuous counter-current extraction system with liquid propane, the ratio 01 liquid propane to oil and the contacting temperature being selected to form two liquid phases difiering in density, said temperature being higher than the highest temperature at which the tocopherol-containing oil and the liquid propane would be completely miscible at the selected ratio; the less dense phase containing the bulk of the tocopherols, propane, and a minor amount of the fatty oil and the more dense phase containing the remainder of the tocopherols and propane and the bulk of the fatty oil, separating the less dense phase from the more dense phase and removing the propane contained in the less dense phase to recover an oil fraction enriched in tocopherols.

4. The process of treating a tocopherol-containing fatty oil which comprises, contacting the tc0phero1-C0ntainillg oil in a continuous countercurrent extraction system with liquid propane, the ratio of liquid propane to oil and the contacting temperature being selected to form two liquid phases difiering in density, said temperature being higher than the highest temperature at which the tocopherol-containing oil and the liquid propane would be completely miscible at the selected ratio; the less dense phase containing the bulk of the tocopherols, propane, and a minor amount of the fatty oil and the more dense phase containing the remainder of the tocopherols and propane and the bulk of the fatty oil, separating the less dense phase from the more dense phase and removing the propane contained in the less dense phase to recover an oil fraction enriched in tocopherols.

5. The process of treating a tocopherol-containing vegetable fatty oil, which comprises, contacting the tocopherol-containing oil in a continuous countercurrent extraction system with a liquefied, normally gaseous paraffinic hydrocarbon solvent; the ratio of liquefied, normally gaseous hydrocarbon solvent to oil and the contacting temperature being selected to form two immiscible liquid phases of diiferent density, said temperature being higher than the highest temperature at which the tocopherol-containing oil and the solvent would be completely miscible at'the selected ratio; the less dense phase containing the bulk 01 the solvent, and tocopherols and a minor amount of the fatty oil and the more dense phase containing the remainder of the solvent and tocopherols and the bulk of the fatty oil; separating the two phases and removing the solvent from the separated less dense phase to recover an oil fraction enriched in tocopherols.

6. A process according to claim 3 in which a temperature gradient is maintained in the extraction system, the highest temperature prevailing at that part of the system at which the less dense phase leaves the system.

7. A process of treating a tocopherol-containing vegetable fatty oil, to obtain a tocopherolrich fraction therefrom which comprises, contacting the oil with liquid propane at a temperature within the range of about -94 C. employing a sufllciently large ratio of propane to oil to form two liquid phases of diflerent density; the less dense phase being composed of the bulk of the propane and tocopherols'and a minor quantity of the fatty oil and the more dense phase being composed of the remainder of the propane and tocopherols and the bulk of the fatty oil, separating the more dense phase from the less dense phase and removing the solvent from the less dense phase to recover a tocopherol-rich fraction.

ARTHUR W. HIXSON. RALPH MILLER.

REFERENCES CITED The following references are of record in the the 0! this patent:

UNITED STATES PATENTS 

5. THE PROCESS OF TREATING A TOCOPHEROL-CONTAING VEGETABLE FATTY OIL, WHICH COMPRISES, CONTACTING THE TOCOPHEROL-CONTAINING OIL IN A CONTINUOUS COUNTERCURRENT EXTRACTION SYSTEM WITH A LIQUEFIED, NORMALLY GASEOUS PARAFFINIC HYDROCARBON SOLVENT; THE RATIO OF LIQUEFLED, NORMALLY GASEOUS HYDROCARBON SOLVENT TO OIL AND THE CONTACTING TEMPERATURE BEING SELECTED TO FORM TWO IMMISCIBLE LIQUID PHASES OF DIFFERENT DENSITY, SAID TEMPERATURE BEING HIGHER THAN THE HIGHEST TEMPERATURE AT WHICH THE TOCHOPHEROL-CONTAINING OIL AND THE SOLVENT WOULD BE COMPLETELY MISCIBLE AT THE SELECTED RATIO; THE LESS DENSE PHASE CONTAINING THE BULK OF THE SOLVENT, AND TOCOPHEROLS AND A MINOR AMOUNT OF THE FATTY OIL AND THE MORE DENSE PHASED CONTAINING THE REMAINDER OF THE SOLVENT AND TOCOPHEROLS AND THE BULK OF THE FATTY OIL; SEPARATING THE TWO PHASES AND REMOVING THE SOLVENT FROM THE SEPARATED LESS DENSE PHASE TO RECOVER AN OIL FRACTION ENRICHED IN TOCOPHEROLS. 